The invention relates generally to power-driven conveyors and more particularly to belt conveyors and associated methods in which conveyor belts having magnetic properties are repelled or are attracted by controllable electromagnets to control belt position to reduce friction or otherwise improve conveyor performance.
Permanent magnets have been used in belt and chain conveyors to reduce friction between belts and conveyor frames and to levitate belts by the force of magnetic repulsion and to prevent belts from rising out of their tracks by the force of magnetic attraction. Permanent magnets in a conveyor frame form magnetic fields that interact with permanent magnets or metallic materials in a conveyor belt to apply forces on the belt that can, for example, be directed to reduce the frictional contact between the belt and the conveyor frame. The strength and arrangement of the magnets is selected for the specific application. Often, however, conveyor operating conditions, such as belt load and belt speed, can change. The change in operating conditions may change the belt dynamics enough that the strength and arrangement of the permanent magnets are suboptimal for the changed operating condition.